PROJECT SUMMARY The purpose of REACTIVE OXYGEN SPECIES CORE A is to provide state-of-the-art measurements of reactive oxygen species (ROS), identify the sources of ROS and assist with ROS studies in intact cells and cellular fractions, ex vivo and in vivo for participants of the PPG. Core A will assist with preparation and processing of various biological samples for analysis using Electron Spin Resonance (ESR) spectroscopy, High Performance Liquid Chromatography (HPLC) and fluorescent spectroscopy. This Core facility has ? supported numerous studies of superoxide (O2 ), hydrogen peroxide (H2O2) and NO in vascular cells and tissue. This facility will significantly enhance the work of the individual laboratories and will enhance collaborations between participants of the PPG. Specifically, the Core A will: 1. Offer expertise, facilities, and training for individuals in performing measurements of ROS, NO and peroxynitrite using ESR spectroscopy, HPLC and fluorescent spectroscopy. 2. Provide assistance with state-of-the-art in vitro, ex vivo and in vivo measurements of ROS, NO and peroxynitrite in cells and tissues for participants of the PPG. 3. Develop techniques and refine existing methods for measurement of ROS, NO and peroxynitrite in cells and tissues. The core leader, Dr. Dikalov, is an expert in in vitro and ex vivo measurements of ROS and NO in vascular cells and tissues and has been at the forefront in developing new methodologies for ROS detection. Much of his work has been focused on development of new ESR and HPLC based techniques for in vitro and in vivo measurements of ROS. REACTIVE OXYGEN SPECIES CORE A will develop new methods and refine existing techniques for measurements of ROS in cells and relevant tissues using ESR probes, boronate-based peroxynitrite fluorescent probes and redox sensitive GPF fluorescent protein targeted to specific intracellular organelles. The application of these methods will enhance the ability of the individual project leaders to test their hypotheses and design new studies as necessary to advance their work.